1. Field of the Invention
The invention relates to an electrical plug the kind used on electrically operated equipment, particularly to improvements into the components and the way all the components within the plug are attached and secured without the function of screws for this purpose.
2. Description of the Related Art
Electrical plugs including on electrically operated equipment are well known in the art. AC power plugs and sockets are devices that allow electrically operated equipment to be connected to the primary alternating current power supply in a building. Plugs and sockets for portable appliances started becoming available in 1880s'.
Generally the plug is the movable contact attached to an electrically operated device's mains cable, and the socket is fixed on equipment or a building structure and connected to an energized electrical circuit. The plug has protruding prongs, blades, or pins (referred to as male) that fit into matching slots or holes (called female) in the sockets.
As electricity became a common method of operating labour-saving appliances, a safe means of connection to the electricity system other than using a light socket was needed. According to British Author John Mellanby the first plug and socket in England was introduced by T. T. Smith in 1883, and there were two-pin designs by 1885, one of which appears in the General Electric Company Ltd. Gustav Binswanger, a German immigrant who founded the (British) General Electric Company Ltd, obtained a patent (GB189516898) in 1895 for a plug and socket using a concentric (co-axial) contact system.
An early electrical plug and socket was invented by Harvey Hubbelll and patented in 1904. Hubbell's first design was a socket which screwed into a lamp holder (like the early lamp holder plugs), but with a separable plug with pins or blades (U.S. Pat. No. 774,250).
The German Schuko-system plug was patented by Albert Büttner in 1926. The current American version of the earthed plug, with two parallel blades and a round earthing pin, was invented by Philip F. Labre, while he was attending the Milwaukee School of Engineering. He was issued an US patent for an earthed socket and plug in 1928.
In the prior art, the most conventional male and female electrical plugs replacements in use require a metal holder with a hole on its center to be attached to the wires with screws. Although these fixes tend to work, attaching the wires into these holders with the screws is difficult and it takes a considerable amount time depending of the model and design. Further, the most common plugs replacements use screws to keep the cord tightened and to keep the cover secured to the holder of the electrical contact.